Update file-storage.mdx

Author: mnapoli

docs/laravel/file-storage.mdx

@@ -61,7 +61,7 @@ but doing this will not let your application work locally. A better solution, bu
     |--------------------------------------------------------------------------
     */
 
-   'public' => env('FILESYSTEM_DISK', 'public_local'),
+   'public' => env('FILESYSTEM_DISK_PUBLIC', 'public_local'),
 
     ...